Means for indicating current impulses



Dec. 30, 1930; Q LOHAUS 1,786,666

MEANS FOR INDICATING CURRENT IMPULSES Filed Sept. 50, 1926 Patented Dec.,30, 1930 UNITED. STATES PATENT. OFFICE,

o'rro oirAUs, or rennin-seriousness, GERMANY, ,ASYVSIGNOR roAKTIENGESELL- scrum MIX nn GENEST, or BERLIN-SCHONEIBERG, casualty MEANSFOR INDICATING' CURRENT IMPULSES 4 Application filed September a0, 1926,Serial No. 138,677, and in Germany lune so, 1925.

This invention relatesto a system for detecting current impulses of suchshort duraconstruction are too inert to respond to these impulses.

The present invention provides a system which instead of causing suchimpulses to react directly upon a relay, causes them to release a flowof. electrical energy of longer duration than that of the impulses, thatis to say, of sufficient duration to operate the relay or another inertdevice of this kind. 7

The said system makes use of electron tubes.

According to this invention there s provided a system for detecingcurrent impulses present in an electrical COIld'L1CtOI' Wh1ChCOm prisesmeans for receivinga momentary current impulse and conveyingthe same tothe grid of an electron tube, the anode circuit of which is arranged tocontrol an indicator and means arranged in the grid circuit so that themomentary impulse received thereby causes a prolonged accumulation ofelectrons upon the grid which varies the electrical properties of theanode circuit and causes the said indicator to operate for at least acorrespondingly prolonged period. y

Several embodiments of the present inven tion are illustrateddiagrammatically in the accompanying drawings, in which':

Figure 1 illustratesa system in which the electron tube is connected attwo points to the said conductor. Figures 2 to 4 illustrate systems inwhich the electron tube has only one point of connection tothisconductor. V p

Other examples of systems are indicated in the description. g s

In the construction illustrated in Figure 1, the grid 1 of the electrontube 2 is connected by a capacity 3 to a conductor 4, in which it isdesired to detect the presence of current impulses. The grid 1 is alsoconnected by means of a variable condenser 5 with the earth 6. Avariable resistance 7 is connected in series with the capacity 3 and thecondenser 5. The filament 8 of the electron tube 2 is also connectedthrougha capacity 9 to the conductor 4 and at the sametime to the earth6 by means of the capacity 0. tion that electro-magnetic relays of theusual 1 A resistance 12 and a condenser 13 are connected in parallelbetween the filament battery 10 ofthe cathode 8 and the grid 1. A relay11 is arranged in the anode circuit of the electron tube 2 and isarranged to control a detector circuit hereinafter descr'ibedur When theconductor 4 carries alternating .60

current, thecurrents which are passed therefrom through the capacities 3and time equalized by the adjustment of the condenser 5 and theresistance 7 so that no charging of the grid 1 takes place.

With the condenser 5 andthe resistance 7 adjusted in the mannerdescribed, a steady anode current passes constantly through the electrontube 2and energizes the relay 11 which is arranged, when so energized,to maintain a contact device 11a in the open position so as to break acircuitwhich when closed is arranged to actuate an electric bell 14. 11bdesignates a suitable spring which normally tends to close the switch11a.

. Current impulses, which are transmitted the length of the conductor 4will first arrive at one of the capacities 3 or 9 and then at the other.and so cause a potential difierence to be produced between thecapacities 3 and 9;

If a negative portion of a current impulse acts upon the grid l, whichthus becomes negatively charged,- electrons will not flow from thecathode 8 to the grid as the electrons are themselves negative. If,however, the passage of such a wave along the conductor 4 momentarilyinfluences the grid 1 positively, electrons pass from the cathode 8 tothe grid. .When the impulse has ceased to influence the grid 1 theaccumulation of electrons thereon, which the impulse has caused, remainand constitute a negative charge upon the grid which causes the anodecurrent of the tube 2 to fall so that the relay 11 becomes sufficientlydc-energized to permit the contact 11a to complete the circuit which isarranged to actuate the bell 14. The contact 11a remains closed untilthe negative charge upon the grid has been gradually equalized sired, bearranged to be maintained closed after the relay 11 has beende-energized.

It is to be observed that when the impulse influences the gridpositively in the manner described, a momentary increase in the anodecurrent results, but this increase merely enhances the effort of therelay 11 to maintain the contact 11a in the open position.

Referring now to the modified system illustrated in Figure 2, the grid 1of the electron tube 2 is connected through a condenser 14 and acapacity 3 to the conductor 4 which is under observation and through aresistance 15 to the earth 6. The resistance 15 may, for example, be apure ohmic resistance, a self induction coil, a capacity or any desiredcombination of such means. A relay 11 is included in the anode circuitas in the system above described with respect to Figure 1.

The capacity of the condenser 3 is arranged to be so small that noeffective energy derived from normal currents flowing in the conductor 4will penerate through the said condenser to the grid 1 of the electrontube 2. The condenser 3 is, however, effectively infiuenced by impulses.

If, therefore, such a current impulse passes through the conductor 4, afall of potential occurs at the resistance 15 which acts upon the grid 1through the condenser 14. If the grid becomes positive through thiscurrent impulse, electrons flow from the cathode 8 to the grid, on whichthey accumulate. These electrons, after the current impulse has takenplace. cannot return to the cathode immediately, but the charge, whichthey form, is equalized slowly over the incompletely insulating glasswall ofthe electron tube or over a high ohmic resistance connected incircuit between the grid 1 and the cathode 8 such, for example, as theresistance 12 illustrated in Figure 1. The anode current of the tube 2falls as a result, so that the relay 11 is effectively de-energized asin the system described with reference to Figure 1.

Instead of the capacity or coupling condenser 3 any equivalent means maybe used for connecting the grid 1 to the conductor The resistance 15 ispreferably a pure ohmic resistance of a few ohms only.

The systems represented in Figures 3 and 4 are to indicate connectionsto the earth which may happen to arise for a short time so as to producea current impulse.

Such earth connections are assumed in Figures 3 and 4 to have takenplace, the conductors 4 being joined through a coil 16 to the earth 6.The object of the arrangements shown in Figures 8 and 4 is to indicatethese earth connections to which conductors of any plant or device, suchas the conductor containing the coil 16, may be subjected.

These conductors 16, 6 (Figures 3 and 4) are each surrounded by a ringcoil 17 In thesystem disclosed in Figure 3, each of the ends of the coil17 is connected through a condenser 18 to the grid 1 of an electron tube2. The two cathodes 8 are included in the same heating circuit. A centretapping of the coil 17 is connected to earth at 19. This system is anexample illustrating the manner in which two electron tubes can beemployed, and is arranged to produce a similar effect upon the relay 11as in the previously described system.

Vita the arrangement illustrated in Figure 4, the coil 17 is connectedto a capacity 20 so as to form an' oscillatory circuit. A currentimpulse which passes through the coil 16 to the earth 6 strikes theoscillatory circuit 17, 20, so that the grid 1 of the electron tube 2 isnegatively charged, whether the current impulse flows in the direction4, 16, 6 or in. the opposite direction 6, 16, 4.

Each of these examples causes a short current impulse to release astream of electrons which are accumulated upon the grid 1 for asufficient duration to effect the operations of the relay 11 in themanner previously described with reference to Figures 1 to 3.

WVha-t I claim and desire to secure by Letters Patent is 1. A system fordetecting current impulses present in an electrical conductor whichcomprises means for receiving a momentary current impulse and conveyingthe same to the grid of an electron tube, the anode circuit of which isarranged to control an indicator, and means arranged in the grid circuitso that the momentary impulse received thereby causes a prolongedaccumulation of electrons upon the grid which varies the electricalproperties of the anode circuit and causes the said indicator to operatefor at least a correspondingly prolonged period.

2. A system for detecting current impulses in an electrical conductorwhich comprises a capacity arranged adjacent the conductor so as toreceive a momentary current impulse and which is connected to the gridof an electron tube the anode circuit of which includes a relay arrangedto control an indicator and a resistance connecting the said grid to thecathode of the electron tube so that the momentary current impulsereceived by the grid causes a prolonged accumulation of electrons uponthe grid which effectively de-energizes the said relay and releases thearmature thereof to close the indicator circuit for at least acorrespondingly prolonged period.

OTTO LOHAUS.

